Artificial Lawn, in Particular an Artificial Grass Sports Field

ABSTRACT

The invention relates to an artificial lawn, in particular an artificial grass sports field, comprising a substrate to which artificial grass fibres provided with additives are attached, which additives undergo a color change in response to an external stimulus. The object of the invention is to provide an artificial lawn as referred to in the introductory paragraph which is capable of displaying a range of colors in a simpler and more effective manner. According to the invention, the artificial grass fibres provided with an additive are attached to the substrate in the form of various groups of artificial grass fibres, each provided with a specific additive, wherein each specific additive of a group of artificial grass fibres undergoes a color change in response to a specific external stimulus. In this way a more versatile artificial lawn is realized, which can be used for various applications, and wherein a new group of artificial grass fibres can be activated to effect the color change each time by using a different, specific external stimulus.

The invention relates to an artificial lawn, in particular an artificial grass sports field, comprising a substrate to which artificial grass fibres provided with additives are attached, which additives undergo a color change In response to an external stimulus.

Such artificial lawns and synthetic fibres are widely used at present, for example as a base for sports fields and in stadiums and also as an artificial grass base for embankment and dyke stabilization. The synthetic fibre is usually made in one color, viz. green, so as to make it resemble natural grass as much as possible. On the other hand, fibres of another color may be worked into such an artificial lawn, for example to show an image or other artistic expression or form the lines in an artificial grass sports field.

The artificial lawns that are currently being used, however, have been designed and installed for a single (sports) application, whilst in addition it is not allowed in certain sports (such as soccer) to have an image or other artistic expression show up in the field. Furthermore, any images or artistic expressions are currently formed on the field (and on the artificial grass fibres) by means of paint. The extent to which the paint adheres to the fibre is limited, however, as a result of which the colors fade with the passage of time, so that the image must be formed anew after some time.

The object of the invention is to overcome these drawbacks and to provide a more multifunctional artificial lawn as referred to in the introductory paragraph which is capable of displaying a range of colors in a simpler and more effective manner.

According to the invention, the artificial grass fibres provided with an additive are attached to the substrate in the form of various groups of artificial grass fibres, each provided with a specific additive, wherein each specific additive of a group of artificial grass fibres undergoes a color change in response to a specific external stimulus.

In this way a more versatile artificial lawn is realized, which can be used for various applications, and wherein a new group of artificial grass fibres can be activated to effect the color change each time by using a different, specific external stimulus.

In a specific embodiment, each group of artificial grass fibres provided with a specific additive is arranged on the substrate in a specific pattern, which specific pattern may optionally correspond to the pattern of lines of a specific sport to be practiced on the artificial lawn.

According to the invention, the color change is reversible, so that the effect can occur several times and the fibre will thus retain its functionality for long period of time. Artificial lawns comprising such synthetic fibres thus have a wider range of applications, as a multifunctional lawn is realized in this way.

In a functional embodiment, the additives may undergo the color change under the influence of a mechanical load, whilst in another embodiment the additives undergo the color change under the influence of a thermal load.

In yet another embodiment, the additives may undergo the color change under the influence of light, wherein the additives furthermore undergo the color change under the influence of a changing angle of incidence of the light.

Preferably, the additives are at least partially externally applied to the synthetic fibre, whilst in another embodiment the additives are at least partially incorporated in the synthetic fibre.

In a functional embodiment, the additives may comprise a pigment, which pigment may successively be a thermochromic, a fluorescent, a phosphorescent, a pearlescent, a pH-sensitive or an electrochromic pigment. These pigments are referred to as effect pigments.

The invention will now be explained in more detail with reference to a drawing, in which:

FIG. 1 shows an embodiment of an artificial lawn provided with synthetic fibres according to the invention;

FIG. 2 shows another embodiment of an artificial lawn provided with synthetic fibres according to the invention.

For a clearer understanding of the invention, like parts will be indicated by the same numerals in the description of the figures below.

FIGS. 1 and 2 show a few embodiments of an artificial lawn in which a synthetic fibre according to the invention can be used. In both figures, the artificial lawn comprises a substrate or carrier 1, to which several synthetic fibres 2 are attached at the locations indicated at 3, for example by tufting. The extruded synthetic fibre 2 may be attached to the substrate either individually or in the form of a bundle of (for example twined) fibres 2 a-2 c.

In another embodiment, as shown in FIG. 1, the synthetic fibre according to the invention may be a monofilament. In this embodiment, too, several monofilaments may be twined to form a bundle, after which each bundle is attached to the substrate 1. In FIG. 1, the substrate has an open structure and is composed of a grid of supporting yarns 1 a-1 b, to which the synthetic fibres 2 are attached.

According to the invention, the synthetic fibres 2 are provided with additives that undergo a color change under the influence of an external stimulus. More specifically, said color change is reversible. In a specific embodiment as already explained above, the additives may undergo the color change under the influence of light. When the synthetic fibre according to the invention is used in an artificial grass sports field, for example, several line patterns may be provided (in dependence on the various sports that can be practiced on the field), which line patterns are each provided in the sports field by using one specific additive for each respective type of sport, which additive will undergo a color change under the influence of light having a specific wavelength. Thus, a line pattern that is desired at a particular moment can be created in dependence on the lighting of the sports field by using a suitable additive.

Such an artificial grass sports field is depicted in FIG. 3 with reference numeral 10. The artificial grass sports field is built up according to for example the construction shown in FIG. 1 or 2, that is consisting of a substrate 1 to which synthetic fibres 2 are attached. In this artificial grass sports field 10 are two different line patterns 11 (for soccer) and 12 (for field hockey) present. Each line pattern is formed by additional groups of synthetic fibres 2′ and 2″ respectively. Each additional group of synthetic fibres 2′ and 2″ respectively is provided according to the invention with a specific additive for said group. Each additive of one of the groups synthetic fibres 2′-2″ undergoes a color change under the influence of a specific external stimulus which is specific for said additive, which specific external stimulus differs from the specific external stimulus of the additive of the other one of the groups synthetic fibres 2′-2″.

The color of the different groups synthetic fibres 2′-2″ can be for example standard green, which color changes into white (or yellow or another striking colors) once the specific group synthetic fibres is subjected to a specific external stimulus, which is specific for the additive present in these fibres/Since the color change is preferably reversible under the influence of an external stimulus (in this case by being illuminated with light having a specific frequency), the color change will be reversed when said external stimulus (the light having the specific frequency) is removed, and the synthetic fibre will return to its original standard appearance. Since the color change is reversible, it can be realized time and again.

In another embodiment the external stimulus can be a heat stimulus, wherein each different additive corresponding with a certain group of synthetic fibres 2′-2″ undergoes the color change at a certain, different temperature.

In another embodiment, the color change can be realized under the influence of a thermal load, which is very suitable for use in artificial grass sports fields on which contact sports are practiced. Think in this connection of sliding tackles and the like, for example, in which case the heat that is produced by a sliding tackle shows up in the artificial grass sports field.

It will be apparent that the additives as described herein can be applied to or incorporated in the synthetic fibre in various ways, for example during the extrusion process, whether or not prior to or after possible stretching of the synthetic fibre.

In another embodiment, in which a phosphorescent pigment is used as the color-changing additive, about 10 wt. % of phosphorescent pigment, usually referred to as Lumilux green, can be added to the. raw material PE (polyethylene) besides the usual additives, for example during extrusion of the synthetic fibre. The addition of said color-changing additive to the extrusion material from which the synthetic fibre is extruded results in an effective afterglowing effect in conditions in which the light intensity is low low (twilight, evening or night). 

1. An artificial lawn, in particular an artificial grass sports field, comprising a substrate to which artificial grass fibers provided with additives are attached, which additives undergo a color change in response to an external stimulus, wherein the artificial grass fibers provided with an additive are attached to the substrate in the form of various groups of artificial grass fibers, each group provided with a specific additive, wherein each specific additive of a group of artificial grass fibers undergoes a color change in response to a specific external stimulus.
 2. The artificial lawn according to claim 1, wherein each group of artificial grass fibers provided with a specific additive is arranged on the substrate in a specific pattern.
 3. An The artificial lawn according to claim 1, wherein said specific pattern corresponds to the pattern of lines of a specific sport to be practiced on the artificial lawn.
 4. The artificial lawn according to claim 1, wherein the color change is reversible.
 5. The artificial lawn according to claim 1, wherein the additives undergo the color change under the influence of a mechanical load.
 6. The artificial lawn according to claim 1, wherein the additives undergo the color change under the influence of a thermal load.
 7. The artificial lawn according to claim 1, wherein the additives undergo the color change under the influence of light.
 8. The artificial lawn according to claim 1, wherein the additives undergo the color change under the influence of a changing angle of incidence of the light.
 9. The artificial lawn according to claim 1, wherein the additives are at least partially externally applied to the artificial grass fibers.
 10. The artificial lawn according to claim 1, wherein the additives are at least partially incorporated in the artificial grass fibers.
 11. The artificial lawn according to claim 1, wherein said additives comprise a pigment.
 12. The artificial lawn according to claim 1, wherein said additives comprise a thermochromic pigment.
 13. The artificial lawn according to claim 1, wherein said additives comprise a fluorescent pigment.
 14. The artificial lawn according to claim 1, wherein said additives comprise a phosphorescent pigment.
 15. The artificial lawn according to claim 1, wherein said additives comprise a pearlescent pigment.
 16. The artificial lawn according to claim 1, wherein said additives comprise a pH-sensitive pigment.
 17. The artificial lawn according to claim 1, wherein said additives comprise an electrochromic pigment.
 18. An artificial grass fiber provided with an additive wherein said additive undergoes a color change in response to a specific external stimulus.
 19. The artificial grass fiber of claim 18 wherein the specific external stimulus is selected from the group consisting of a mechanical stimulus, heat, and light.
 20. The artificial grass fiber of claim 18 wherein the additive is a pigment selected from the group consisting of a thermochromic pigment, a fluorescent pigment, a phosphorescent pigment, a pearlescent pigment, a pH-sensitive pigment, and an electrochromic pigment. 